#213: Write unit tests for the transaction command

#213 (closed): Unit tests for tx.py. Create unit tests for:

• handle_intermediaries_transactions,
• send_transaction,
• generate_and_send_transaction,
• display_sent_tx,
• check_transaction_values,
• generate_unlocks,
• generate_output,

Modifies test for get_list_input_for_transaction,

Changes how patched_get_sources() works:

• create a dictionary for test sources.

Deals with other issues:

• Close #197: one test for auth_method()
• Close #282 (closed): split patched.py
• Close #335 (closed): two functions are testing transaction_amount()